ans = 0
gets.to_i.times do |i|
    s = gets.chomp
    neg = false
    num = 0
    if s[0] == '-'
        neg = true
        s = s[1...s.size]
    end

    if s.include?('.')
        pos = s.index('.')
        a = s[0...pos]
        b = s[pos + 1...s.size]
        b += "0" * (10 - b.size)
        num = a.to_i * (10 ** 10) + b.to_i
    else
        num = s.to_i * (10 ** 10)
    end

    if neg
        ans -= num
    else
        ans += num
    end
end

if ans == 0
    puts "0.0000000000"
else
    ans = ans.to_s
    if ans.chars.count {|c| c != '-' } == 10
        ans.insert(ans[0] == '-' ? 1 : 0, '0')
    end
    ans.insert(ans.size - 10, '.')
    puts ans
end